Semiconductor device and method of manufacture

ABSTRACT

A method of applying and then removing a protective layer over a portion of a gate stack is provided. The protective layer is deposited and then a plasma precursor is separated into components. Neutral radicals are then utilized in order to remove the protective layer. In some embodiments the removal also forms a protective by-product which helps to protect underlying layers from damage during the etching process.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as, for example, personal computers, cell phones, digital cameras,and other electronic equipment. Semiconductor devices are typicallyfabricated by sequentially depositing insulating or dielectric layers,conductive layers, and semiconductor layers of material over asemiconductor substrate, and patterning the various material layersusing lithography to form circuit components and elements thereon.

The semiconductor industry continues to improve the integration densityof various electronic components (e.g., transistors, diodes, resistors,capacitors, etc.) by continual reductions in minimum feature size, whichallow more components to be integrated into a given area. However, asthe minimum features sizes are reduced, additional problems arise thatshould be addressed.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a perspective view of a finFET device in accordancewith some embodiments.

FIG. 2 illustrates formation of source/drain regions in accordance withsome embodiments.

FIG. 3 illustrates a removal of a dummy gate electrode in accordancewith some embodiments.

FIG. 4 illustrates a deposition of a gate dielectric, a barrier layer,and a protective layer in accordance with some embodiments.

FIG. 5 illustrates an annealing process in accordance with someembodiments.

FIGS. 6A-6C illustrate a first etching process in accordance with someembodiments.

FIGS. 7A-7C illustrate a second etching process in accordance with someembodiments.

FIG. 8 illustrates a removal of a solid by-product material inaccordance with some embodiments.

FIG. 9 illustrates a formation of a remainder of a gate stack inaccordance with some embodiments.

FIG. 10 illustrates a formation of a capping layer in accordance withsome embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Embodiments will be described below with respect to specificembodiments, including protective thin films and methods for preventingsurface damage of a 3D structure during formation of FinFET devices.Embodiments, however, are not intended to be limited, and may beutilized in a wide variety of embodiments beyond the formation of FinFETdevices.

With reference now to FIG. 1, there is illustrated a perspective view ofa semiconductor device 100 such as a finFET device. In an embodiment thesemiconductor device 100 comprises a substrate 101 and first trenches103. The substrate 101 may be a silicon substrate, although othersubstrates, such as semiconductor-on-insulator (SOI), strained SOI, andsilicon germanium on insulator, could be used. The substrate 101 may bea p-type semiconductor, although in other embodiments, it could be ann-type semiconductor.

The first trenches 103 may be formed as an initial step in the eventualformation of first isolation regions 105. The first trenches 103 may beformed using a masking layer (not separately illustrated in FIG. 1)along with a suitable etching process. For example, the masking layermay be a hardmask comprising silicon nitride formed through a processsuch as chemical vapor deposition (CVD), although other materials, suchas oxides, oxynitrides, silicon carbide, combinations of these, or thelike, and other processes, such as plasma enhanced chemical vapordeposition (PECVD), low pressure chemical vapor deposition (LPCVD), oreven silicon oxide formation followed by nitridation, may be utilized.Once formed, the masking layer may be patterned through a suitablephotolithographic process to expose those portions of the substrate 101that will be removed to form the first trenches 103.

As one of skill in the art will recognize, however, the processes andmaterials described above to form the masking layer are not the onlymethod that may be used to protect portions of the substrate 101 whileexposing other portions of the substrate 101 for the formation of thefirst trenches 103. Any suitable process, such as a patterned anddeveloped photoresist, may be utilized to expose portions of thesubstrate 101 to be removed to form the first trenches 103. All suchmethods are fully intended to be included in the scope of the presentembodiments.

Once a masking layer has been formed and patterned, the first trenches103 are formed in the substrate 101. The exposed substrate 101 may beremoved through a suitable process such as reactive ion etching (RIE) inorder to form the first trenches 103 in the substrate 101, although anysuitable process may be used. In an embodiment, the first trenches 103may be formed to have a first depth of less than about 5,000 Å from thesurface of the substrate 101, such as about 2,500 Å.

However, as one of ordinary skill in the art will recognize, the processdescribed above to form the first trenches 103 is merely one potentialprocess, and is not meant to be the only embodiment. Rather, anysuitable process through which the first trenches 103 may be formed maybe utilized and any suitable process, including any number of maskingand removal steps may be used.

In addition to forming the first trenches 103, the masking and etchingprocess additionally forms fins 107 from those portions of the substrate101 that remain unremoved. For convenience the fins 107 have beenillustrated in the figures as being separated from the substrate 101 bya dashed line, although a physical indication of the separation may ormay not be present. These fins 107 may be used, as discussed below, toform the channel region of multiple-gate FinFET transistors. While FIG.1 only illustrates three fins 107 formed from the substrate 101, anynumber of fins 107 may be utilized.

The fins 107 may be formed such that they have a width at the surface ofthe substrate 101 of between about 5 nm and about 80 nm, such as about30 nm. Additionally, the fins 107 may be spaced apart from each other bya distance of between about 10 nm and about 100 nm, such as about 50 nm.By spacing the fins 107 in such a fashion, the fins 107 may each form aseparate channel region while still being close enough to share a commongate (discussed further below).

Once the first trenches 103 and the fins 107 have been formed, the firsttrenches 103 may be filled with a dielectric material and the dielectricmaterial may be recessed within the first trenches 103 to form the firstisolation regions 105. The dielectric material may be an oxide material,a high-density plasma (HDP) oxide, or the like. The dielectric materialmay be formed, after an optional cleaning and lining of the firsttrenches 103, using either a chemical vapor deposition (CVD) method(e.g., the HARP process), a high density plasma CVD method, or othersuitable method of formation as is known in the art.

The first trenches 103 may be filled by overfilling the first trenches103 and the substrate 101 with the dielectric material and then removingthe excess material outside of the first trenches 103 and the fins 107through a suitable process such as chemical mechanical polishing (CMP),an etch, a combination of these, or the like. In an embodiment, theremoval process removes any dielectric material that is located over thefins 107 as well, so that the removal of the dielectric material willexpose the surface of the fins 107 to further processing steps.

Once the first trenches 103 have been filled with the dielectricmaterial, the dielectric material may then be recessed away from thesurface of the fins 107. The recessing may be performed to expose atleast a portion of the sidewalls of the fins 107 adjacent to the topsurface of the fins 107. The dielectric material may be recessed using awet etch by dipping the top surface of the fins 107 into an etchant suchas HF, although other etchants, such as H₂, and other methods, such as areactive ion etch, a dry etch with etchants such as NH₃/NF₃, chemicaloxide removal, or dry chemical clean may be used. The dielectricmaterial may be recessed to a distance from the surface of the fins 107of between about 50 Å and about 500 Å, such as about 400 Å.Additionally, the recessing may also remove any leftover dielectricmaterial located over the fins 107 to ensure that the fins 107 areexposed for further processing.

As one of ordinary skill in the art will recognize, however, the stepsdescribed above may be only part of the overall process flow used tofill and recess the dielectric material. For example, lining steps,cleaning steps, annealing steps, gap filling steps, combinations ofthese, and the like may also be utilized to form and fill the firsttrenches 103 with the dielectric material. All of the potential processsteps are fully intended to be included within the scope of the presentembodiment.

After the first isolation regions 105 have been formed, a dummy gatedielectric 109, a dummy gate electrode 111 over the dummy gatedielectric 109, and first spacers 113 may be formed over each of thefins 107. In an embodiment the dummy gate dielectric 109 may be formedby thermal oxidation, chemical vapor deposition, sputtering, or anyother methods known and used in the art for forming a gate dielectric.Depending on the technique of gate dielectric formation, the dummy gatedielectric 109 thickness on the top of the fins 107 may be differentfrom the gate dielectric thickness on the sidewall of the fins 107.

The dummy gate dielectric 109 may comprise a material such as silicondioxide or silicon oxynitride with a thickness ranging from about 3angstroms to about 100 angstroms, such as about 10 angstroms. The dummygate dielectric 109 may be formed from a high permittivity (high-k)material (e.g., with a relative permittivity greater than about 5) suchas lanthanum oxide (La₂O₃), aluminum oxide (Al₂O₃), hafnium oxide(HfO₂), hafnium oxynitride (HfON), or zirconium oxide (ZrO₂), orcombinations thereof, with an equivalent oxide thickness of about 0.5angstroms to about 100 angstroms, such as about 10 angstroms or less.Additionally, any combination of silicon dioxide, silicon oxynitride,and/or high-k materials may also be used for the dummy gate dielectric109.

The dummy gate electrode 111 may comprise a conductive material and maybe selected from a group comprising of polysilicon, W, Al, Cu, AlCu, W,Ti, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, TiN, Ta, TaN, Co, Ni, combinationsof these, or the like. The dummy gate electrode 111 may be deposited bychemical vapor deposition (CVD), sputter deposition, or other techniquesknown and used in the art for depositing conductive materials. Thethickness of the dummy gate electrode 111 may be in the range of about 5Å to about 200 Å. The top surface of the dummy gate electrode 111 mayhave a non-planar top surface, and may be planarized prior to patterningof the dummy gate electrode 111 or gate etch. Ions may or may not beintroduced into the dummy gate electrode 111 at this point. Ions may beintroduced, for example, by ion implantation techniques.

Once formed, the dummy gate dielectric 109 and the dummy gate electrode111 may be patterned to form a series of stacks 115 over the fins 107.The stacks 115 define multiple channel regions located on each side ofthe fins 107 beneath the dummy gate dielectric 109. The stacks 115 maybe formed by depositing and patterning a gate mask (not separatelyillustrated in FIG. 1) on the dummy gate electrode 111 using, forexample, deposition and photolithography techniques known in the art.The gate mask may incorporate commonly used masking and sacrificialmaterials, such as (but not limited to) silicon oxide, siliconoxynitride, SiCON, SiC, SiOC, and/or silicon nitride and may bedeposited to a thickness of between about 5 Å and about 200 Å. The dummygate electrode 111 and the dummy gate dielectric 109 may be etched usinga dry etching process to form the patterned stacks 115.

Once the stacks 115 have been patterned, the first spacers 113 may beformed. The first spacers 113 may be formed on opposing sides of thestacks 115. The first spacers 113 may be formed, for example, by blanketdepositing a spacer layer (not separately illustrated in FIG. 1) on thepreviously formed structure. The spacer layer may comprise SiN,oxynitride, SiC, SiON, SiOCN, SiOC, oxide, and the like and may beformed by methods utilized to form such a layer, such as chemical vapordeposition (CVD), plasma enhanced CVD, sputter, and other methods knownin the art. The spacer layer may comprise a different material withdifferent etch characteristics or the same material as the dielectricmaterial within the first isolation regions 105. The first spacers 113may then be patterned, such as by one or more etches to remove thespacer layer from the horizontal surfaces of the structure, to form thefirst spacers 113.

In an embodiment the first spacers 113 may be formed to have a thicknessof between about 5 Å and about 500 Å. Additionally, once the firstspacers 113 have been formed, a first spacer 113 adjacent to one stack115 may be separated from a first spacer 113 adjacent to another stack115 by a distance of between about 5 nm and about 200 nm, such as about20 nm. However, any suitable thicknesses and distances may be utilized.

FIG. 2 illustrates a removal of the fins 107 from those areas notprotected by the stacks 115 and the first spacers 113 and a regrowth ofsource/drain regions 201. The removal of the fins 107 from those areasnot protected by the stacks 115 and the first spacers 113 may beperformed by a reactive ion etch (RIE) using the stacks 115 and thefirst spacers 113 as hardmasks, or by any other suitable removalprocess. The removal may be continued until the fins 107 are eitherplanar with (as illustrated) or below the surface of the first isolationregions 105.

Once these portions of the fins 107 have been removed, a hard mask (notseparately illustrated), is placed and patterned to cover the dummy gateelectrode 111 to prevent growth and the source/drain regions 201 may beregrown in contact with each of the fins 107. In an embodiment thesource/drain regions 201 may be regrown and, in some embodiments thesource/drain regions 201 may be regrown to form a stressor that willimpart a stress to the channel regions of the fins 107 locatedunderneath the stacks 115. In an embodiment wherein the fins 107comprise silicon and the FinFET is a p-type device, the source/drainregions 201 may be regrown through a selective epitaxial process with amaterial, such as silicon or else a material such as silicon germaniumthat has a different lattice constant than the channel regions. Theepitaxial growth process may use precursors such as silane,dichlorosilane, germane, and the like, and may continue for betweenabout 5 minutes and about 120 minutes, such as about 30 minutes.

Once the source/drain regions 201 are formed, dopants may be implantedinto the source/drain regions 201 by implanting appropriate dopants tocomplement the dopants in the fins 107. For example, p-type dopants suchas boron, gallium, indium, or the like may be implanted to form a PMOSdevice. In another embodiment, n-type dopants such as phosphorous,arsenic, antimony, or the like may be implanted to form an NMOS device.These dopants may be implanted using the stacks 115 and the firstspacers 113 as masks. It should be noted that one of ordinary skill inthe art will realize that many other processes, steps, or the like maybe used to implant the dopants. For example, one of ordinary skill inthe art will realize that a plurality of implants may be performed usingvarious combinations of spacers and liners to form source/drain regionshaving a specific shape or characteristic suitable for a particularpurpose. Any of these processes may be used to implant the dopants, andthe above description is not meant to limit the present embodiments tothe steps presented above.

Additionally at this point the hard mask that covered the dummy gateelectrode 111 during the formation of the source/drain regions 201 isremoved. In an embodiment the hard mask may be removed using, e.g., awet or dry etching process that is selective to the material of the hardmask. However, any suitable removal process may be utilized.

FIG. 2 also illustrates a formation of an inter-layer dielectric (ILD)layer 203 (illustrated in dashed lines in FIG. 2 in order to moreclearly illustrate the underlying structures) over the stacks 115 andthe source/drain regions 201. The ILD layer 203 may comprise a materialsuch as boron phosphorous silicate glass (BPSG), although any suitabledielectrics may be used. The ILD layer 203 may be formed using a processsuch as PECVD, although other processes, such as LPCVD, may also beused. The ILD layer 203 may be formed to a thickness of between about100 Å and about 3,000 Å. Once formed, the ILD layer 203 may beplanarized with the first spacers 113 using, e.g., a planarizationprocess such as chemical mechanical polishing process, although anysuitable process may be utilized.

FIG. 3 illustrates a cross-sectional view of FIG. 2 along line 3-3′ andalso illustrates a removal of the material of the dummy gate electrode111 and the dummy gate dielectric 109 forming openings 302 exposing thechannel regions of fins 107. In an embodiment the dummy gate electrode111 and the dummy gate dielectric 109 may be removed using, e.g., wet ordry etching processes that utilizes etchants that are selective to thematerial of the dummy gate electrode 111 and the dummy gate dielectric109. In one embodiment the dummy gate electrode 111 may be removed usinga wet etchant such as dilute hydrofluoric acid and hydrogen peroxide.However, any suitable removal process may be utilized. The exposedchannel regions are illustrated in FIG. 3 with portions of the fins 107embedded in first spacers 113 and source/drain regions 201.

FIG. 4 illustrates an intermediate step of forming a metal gateelectrode in the openings 302 shown in FIG. 3. After the channel regionsof the fins 107 have been exposed, a first dielectric material 401 maybe deposited over the complex surfaces of the 3D structure withinopenings 302. In addition and also shown in FIG. 4, the first dielectricmaterial 401 may be deposited over the planarized surfaces of the firstspacers 113 and the ILD layer 203 in the source/drain regions 201 of thefins 107.

The first dielectric material 401 is a high-k material such as HfO₂,HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, LaO, ZrO, Ta₂O₅, combinations ofthese, or the like, deposited through a process such as atomic layerdeposition, chemical vapor deposition, or the like. However, any othersuitable materials, such as silicon oxynitride, may also be utilized.The first dielectric material 401 may be deposited to a thickness ofbetween about 5 Å and about 200 Å, although any suitable thickness maybe utilized.

Optionally, an interfacial layer (not separately illustrated in FIG. 4)may be formed prior to the formation of the first dielectric material401. In an embodiment the interfacial layer may be a material such assilicon dioxide formed through a process such as in situ steamgeneration (ISSG). However, any suitable material or process offormation may be utilized.

Also optional, a first conductive layer (not separately illustrated inFIG. 4) may be formed on the first dielectric material 401. The firstconductive layer may be a metal silicide material such as titaniumsilicon nitride (TSN). In an embodiment the first conductive layer maybe formed using a deposition process such as chemical vapor deposition,although any suitable method of deposition, such as a deposition andsubsequent silicidation, may be utilized to a thickness of between about5 Å and about 30 Å. However, any suitable thickness may be utilized.

As illustrated in FIG. 4, a first metal material layer 405 may be formedadjacent to the first dielectric material 401 as a barrier layer and maybe formed from a metallic material such as TaN, Ti, TiAlN, TaC, TaCN,TaSiN, Mn, Zr, TiN, Ru, Mo, WN, other metal oxides, metal nitrides,metal silicates, transition metal-oxides, transition metal-nitrides,transition metal-silicates, oxynitrides of metals, metal aluminates,zirconium silicate, zirconium aluminate, combinations of these, or thelike. The first metal material layer 405 may be deposited using adeposition process such as atomic layer deposition, chemical vapordeposition, sputtering, or the like, to a thickness of between about 5 Åand about 200 Å, although any suitable deposition process or appropriatethickness may be used.

Once the first metal material layer 405 has been formed to theappropriate thickness, a protection layer 406 is deposited on the firstmetal material layer 405. The protection layer 406 may be asemiconductor material such as a silicon material (e.g., Si), althoughany suitable protective material may be utilized. The protection layer406 may be formed to a thickness of between about 5 Å and 100 Å, such asabout 15 Å. However, any appropriate thickness may be utilized.

The material properties of the protection layer 406 and the methods ofdeposition as described herein, allow for the protection layer 406 toprovide good coverage and for good gap-fill. Additionally, theprotection layer 406 helps to repair weaknesses that may form inportions of the first metal material layer 405 and first dielectricmaterial 401 during anneal and etching of the 3D structure. For example,weaknesses formed in the first metal material layer 405 and/or firstdielectric material 401 at the bottom of the openings 302 during etchingof the 3D structure can lead to metal gate extrusion (MGEX). Otherweaknesses formed at the planarized surface of the ILD layer 203 in thesource/drain regions 201 of the fins 107 may lead to fin top damageduring etching of the 3D structure. These weaknesses may result inmanufacturing defects including substandard breakdown voltages of thesemiconductor device.

These undesirable weaknesses may be repaired or even prevented by usingthe protection layer 406 as a protective layer on the first metalmaterial layer 405 during subsequent anneal and etching processing ofthe 3D structure. By repairing and/or preventing these weaknesses, fewerdefective parts may be manufactured, leading to an increase in overallyield.

The protection layer 406 may be formed through any of a variety ofdeposition techniques, including chemical vapor deposition (CVD), LPCVD(low-pressure chemical vapor deposition), APCVD (atmospheric-pressurechemical vapor deposition), PECVD (plasma-enhanced chemical vapordeposition), physical vapor deposition (PVD), plasma-enhanced atomiclayer deposition (PE-ALD), sputtering, combinations of these, or thelike. In one embodiment, the protection layer 406 is depositedconformally over the 3D structure using a deposition process such asCVD. In this embodiment, the deposition process may be performed at aprocess temperature of between about 300° C. and about 550° C., at apressure of from about 0.1 torr to about 10 torr, for from about 1second to about 180 minutes. However, any suitable deposition process,fitting temperature, or appropriate pressure may be used to form theprotection layer 406.

Turning to FIG. 5, after the protection layer 406 has been deposited, ananneal process 502 is performed for the first dielectric material 401.During the anneal process 502, the semiconductor device 100 is exposedto an oxygen rich environment such that a portion of the protectionlayer 406 becomes infused with oxygen forming oxide bonds with thematerial of the protection layer 406 and modifying a portion of theprotection layer 406 into an oxide layer 506. In an embodiment, theprotection layer 406 may be formed of a silicon (Si) material and theoxide layer 506 may be a silicon oxide (SiO₂) material.

In an embodiment the anneal process 502 may be performed at atemperature of between about 400 C and about 1300 C, such as about 900C, for a time period of between about 0.01 sec and about 100 sec, suchas about 10 sec. Additionally, the anneal process 502 may be performedin an oxidizing ambient environment, such as an environment comprising,oxygen, ozone, water, combinations of these, or the like. However, anysuitable process parameters and ambient conditions may be utilized.

During the anneal process 502 the oxygen within the ambient will reactwith the material of the protection layer 406 to form the oxide layer506. In an embodiment, once the anneal process 502 has been completed,the oxide layer 506 may have a thickness of between about 2 A and about20 A, such as about 15 A, while the remaining portion of the protectionlayer 406 may have a thickness of between about 3 A and about 80 A, suchas about 15 A. However, any suitable dimension may be utilized.

Continuing to FIG. 6A, once the anneal process 502 has completed, theoxide layer 506 portion of the protection layer 406 is removed. In anembodiment, the removal of the oxide layer 506 may be achieved via aplasma etch removal process. However, any suitable removal process maybe used to remove the oxide layer 506.

FIG. 6B illustrates a plasma etch removal process in an etching chamber607 using remote plasma that may be utilized to remove the oxide layer506 from the semiconductor device 100. However, while the embodiment isdescribed with reference to the protection layer 406 for use insemiconductor manufacturing, the embodiments are not limited to asemiconductor manufacturing. Rather, any process that utilizes a plasmaetch removal process may benefit from the embodiments. All suchprocesses and plasma etchants are fully intended to be included withinthe scope of the embodiments.

In an embodiment the etching system 600 may utilize two or moreprecursor materials to remove the oxide layer 506. For example, theetching system 600 may receive precursor materials from a firstprecursor delivery system 605 and a second precursor delivery system 606to generate an etchant used to remove the oxide layer 506 from thesemiconductor device 100. The removal of the oxide layer 506 may beperformed in the etching chamber 607 which receives the first precursormaterial and the second precursor material.

The first precursor delivery system 605 and the second precursordelivery system 606 may work in conjunction with one another to supplythe various different precursor materials to the etching chamber 607. Inan embodiment in which the first precursor material is in a gaseousstate during preparation and storage (e.g., a first precursor materialincluding nitrogen-triflouride (e.g., (NF₃)), the first precursordelivery system 605 may comprise a first precursor material supplier,such as a gas storage tank or a machine to generate the first precursormaterial on an as-needed basis in order to supply it to the plasma block620 (discussed further below).

In another embodiment where the first precursor material is either aliquid or solid precursor material, the first precursor delivery system605 may comprise a carrier gas supply (not individually illustrated) anda precursor canister (also not individually illustrated) arranged inseries. The carrier gas supply may be, e.g., an inert gas and may beused to help “carry” the precursor gas to the plasma block 620 and intothe etching chamber 607 and may be coupled to the precursor canister,which may be utilized to supply a desired precursor (e.g., the firstprecursor material) to the etching chamber 607 by vaporizing orsublimating precursor materials that may be delivered in either a solidor liquid phase. The precursor canister may have a vapor region intowhich precursor material is driven into a gaseous phase so that thecarrier gas may enter the precursor canister and pick-up or carry thegaseous precursor material out of the precursor canister and towards theetching chamber 607.

The first precursor delivery system 605 is connected to and supplies thefirst precursor material to a first precursor gas controller 611, whichmay supply the first precursor material to the plasma block 620 beforethe first precursor material enters the etching chamber 607. In anembodiment the first precursor gas controller 611 may include suchdevices as valves, flow meters, sensors, and the like to control theconnection and delivery rate of the first precursor material to theplasma block 620. The first precursor gas controller 611 may becontrolled and receive instructions from a control unit 619.

The second precursor delivery system 606 may comprise components similarto the first precursor delivery system 605. For example, if the secondprecursor material is in a gaseous state during preparation and storage(e.g., a second precursor material including a nitrogen and hydrogencontaining compound such as ammonia (NH₃)), the second precursordelivery system 606 may comprise a second precursor material supplier,such as a gas storage tank or a machine to generate the second precursormaterial on an as-needed basis. In another embodiment, if the secondprecursor material is in a liquid or solid state during preparation andstorage, the second precursor delivery system 606 may be implementedusing a carrier gas and a sublimation/vaporization process.

The second precursor delivery system 606 is connected to and suppliesthe second precursor material to a second precursor gas controller 612,which may supply the second precursor material to the plasma block 620before the second precursor material enters the etching chamber 607. Inan embodiment the second precursor gas controller 612 may include suchdevices as valves, flow meters, sensors, and the like to control theconnection and delivery rate of the second precursor material to theplasma block 620. The second precursor gas controller 612 receivesinstructions from and is controlled by the control unit 619.

The first precursor gas controller 611 and the second precursor gascontroller 612, upon receiving instructions from the control unit 619,may open and/or close valves so as to connect the first precursordelivery system 605 and the second precursor delivery system 606 to theplasma block 620 and direct the desired precursor materials to theirrespective destinations. In an embodiment, the first precursor gascontroller 611 and the second precursor gas controller 612 willrespectfully direct the first precursor material and the secondprecursor material to the plasma block 620. For example, the firstprecursor gas controller 611 directs the first precursor material to afirst inlet of the plasma block 620 and the second precursor gascontroller 612 directs the second material to a second inlet of theplasma block 620.

Additionally, while a single plasma block 620 is illustrated in FIG. 6B,any number of plasma blocks 620 may additionally be included within theetching system 600 for separately processing the different precursormaterials. For example, in some embodiments, the first precursor gascontroller 611 directs the first precursor material to an inlet of afirst plasma block of a plurality of plasma blocks 620 and the secondprecursor gas controller 612 directs the second precursor material to aninlet of a second plasma block (not separately shown) of the pluralityof plasma blocks 620. In still another embodiment, the first precursorgas controller 611 directs the first precursor material to a mixer (notseparately shown) and the second precursor gas controller 612 directsthe second material to the mixer. According to instructions receivedfrom the control unit 619, the mixer combines appropriate amounts of thefirst precursor material with appropriate amounts of the secondprecursor material to form a desired mixture of the first precursormaterial and the second precursor material. The mixer provides thedesired mixture to an inlet of the plasma block 620.

Once processed by the plasma block 620, a first precursor plasma of thefirst precursor material, a second precursor plasma of the secondprecursor material and/or a compound precursor plasma of the compoundprecursor material are provided, according to instructions of thecontrol unit 619, to one or more plasma inlets of the showerhead 613.The showerhead 613 may be a multiple-zone showerhead utilized todisperse the chosen precursor materials into the etching chamber 607 andmay be designed to evenly disperse the precursor materials in order tominimize undesired process conditions that may arise from unevendispersal. In an embodiment in which two precursor materials areutilized the showerhead 613 may have a dual dispersion design thataccepts both the first precursor plasma (through, e.g., a first plasmainlet) and the second precursor plasma (through, e.g., a second plasmainlet) at the same time and will disperse both the first precursorplasma and the second precursor plasma in an even distribution aroundthe etching chamber 607. The showerhead 613 may have a circular designwith openings dispersed evenly around the showerhead 613 to allow forthe dispersal of the first precursor plasma and the second precursorplasma into the etching chamber 607.

The etching chamber 607 may receive the desired precursor materials andexpose the precursor materials to the surfaces of the semiconductordevice 100, and the etching chamber 607 may be any desired shape thatmay be suitable for dispersing the precursor materials and contactingthe precursor materials with the semiconductor device 100. In theembodiment illustrated in FIG. 6B, the etching chamber 607 has acylindrical sidewall and a bottom. Furthermore, the etching chamber 607may be surrounded by a housing 617 made of material that is inert to thevarious process materials. In an embodiment, the housing 617 may besteel, stainless steel, nickel, aluminum, alloys of these, orcombinations of these.

Within the etching chamber 607 the semiconductor device 100 may beplaced on a mounting platform 615 made of, e.g., aluminum, in order toposition and control the semiconductor device 100 during the etchingprocess. The mounting platform 615 may be rotatable and may includeheating mechanisms in order to heat the semiconductor device 100 duringthe etching process. Furthermore, while a single mounting platform 615is illustrated in FIG. 6B, any number of mounting platforms 615 mayadditionally be included within the etching chamber 607.

The etching chamber 607 may also have pumping channels 621 for exhaustgases to exit the etching chamber 607. A vacuum pump (not shown) may beconnected to the pumping channels 621 of the etching chamber 607 inorder to help evacuate the exhaust gases. The vacuum pump, under controlof the control unit 619, may also be utilized to reduce and control thepressure within the etching chamber 607 to a desired pressure and mayalso be utilized to evacuate precursor materials from the etchingchamber 607 in preparation for the introduction of a purge gas.

FIG. 6C illustrates an embodiment of the plasma block 620 (or plasmagenerator) from FIG. 6B in greater detail. In an embodiment the plasmablock 620 has an inlet port 651 that receives the first precursormaterial from the first precursor gas controller 611 and the secondprecursor material from the second precursor gas controller 612 and anoutlet port 655 that is coupled to deliver a first precursor plasma(converted from the first precursor material) to the showerhead 613. Thefirst precursor material enters the plasma block 620 and passes betweena magnetic core 653 that surrounds a portion of the plasma block 620.The magnetic core 653 is utilized to induce the formation of the firstprecursor plasma from the first precursor material that enters theplasma block 620 before exiting out of the outlet port 655.

The magnetic core 653 may be situated around a portion of the flow paththrough the plasma block 620 from the inlet port 651 to the outlet port655. In an embodiment the magnetic core 653 is one portion of atransformer 652 (illustrated in FIG. 6C with dashed line 652), with aprimary coil 656 forming another portion of the transformer 652. In anembodiment the primary coil 656 may have a winding of between about 100and about 1000 such as about 600.

To generate the desired first precursor plasma from the first precursormaterial and the desired second precursor plasma from the secondprecursor material within the plasma block 650, a short, high-voltagepulse of electricity controlled, e.g., by the control unit 619 (see FIG.6B) may be applied to the primary coil 656. The high-voltage pulse ofelectricity in the primary coil 656 is transformed to a pulse of energyinto the magnetic core 653, which induces the formation of the firstprecursor plasma and the second precursor plasma within the plasma block620. In an embodiment the high-voltage pulse may be between about 10 kHzand about 30 MHz such as about 13.56 MHz, while the temperature isbetween about 50° C. and about 200° C. and with a pressure of betweenabout 1 torr and about 20 torr.

However, while igniting the first precursor material and the secondprecursor material with a magnetic coil is described as one embodiment,other embodiments are not so limited. Rather, any suitable method orstructures may be used to ignite the first precursor material to formthe first precursor plasma and to ignite the second precursor materialto form the second precursor plasma. For example, in other embodiments ahigh voltage pulse may be applied to an electrode (not illustrated)coupled to the plasma block 620, or the first precursor material and thesecond precursor material may be exposed to a ultraviolet radiation thatmay be used to ignite the first precursor material and the secondprecursor material and form the first precursor plasma and the secondprecursor plasma. Any suitable method of ignition and any other suitableplasma inducing device are fully intended to be included within thescope of the embodiments.

The plasma block 620 also comprises an inner housing 657 and aninsulator 659 surrounding the inner housing 657. The insulator 659 maybe used to electrically and thermally isolate the inner housing 657 ofthe plasma block 620. In an embodiment the inner housing 657 enclosesand encapsulates the circular path of the first precursor material andthe second precursor material and (after ignition) the first precursorplasma and the second precursor plasma in order to guide the firstprecursor material and the first precursor plasma through the plasmablock 620.

The plasma block 620 may also comprise a sensor 661 that may be used tomeasure the conditions within the plasma block 620. In an embodiment thesensor 661 may be a current probe used to measure the current and powerof the plasma as part of a feedback loop to the control unit 619 (seeFIG. 6B). In addition, or in a separate embodiment, the sensor 661 mayalso comprise an optical sensor or any other measurement devices thatmay be used to measure and control the plasma generation within theplasma block 620.

Returning to FIG. 6B, the removal of the oxide layer 506 may beinitiated by putting the first precursor into the first precursordelivery system 605. For example, in an embodiment the first precursormaterial may be a material that can work in conjunction with the secondprecursor material as a plasma to remove the material of the oxide layer506. In one embodiment the first precursor material may be a compoundwhich comprises fluorine, such as, for example, fluorine (F₂), sulfurhexafluoride (SF₆), carbon tetrafluoride (CF₄), nitrogen tri-fluoride(NF₃) or the like. However, any suitable etching precursor may beutilized for the first precursor material.

Additionally, the second precursor material may be placed into or formedby the second precursor delivery system 606. In an embodiment to formthe plasma etchant, the second precursor material may be a material thatcan work in conjunction with the first precursor material as a plasma toremove the material of the oxide layer 506. In one embodiment the secondprecursor material may be a compound which comprises hydrogen, forexample, hydrogen (H₂) or a combination of nitrogen (N₂) and hydrogen(H₂) gas, ammonia (NH3), or the like. However, any suitable etchingprecursor may be utilized for the second precursor material.

Once the first precursor material and the second precursor material areready in the first precursor delivery system 605 and the secondprecursor delivery system 606, respectively, the formation of the plasmaetchant may be initiated by the control unit 619 sending an instructionto the first precursor gas controller 611 and the second precursor gascontroller 612 to connect the first precursor delivery system 605 andthe second precursor delivery system 606 to the etching chamber 607 viathe plasma block 620. Once connected, the first precursor deliverysystem 605 can deliver the first precursor material (e.g., NF₃) to theshowerhead 613 through the plasma block 620, with the plasma block 620inducing the formation of the first precursor plasma as the firstprecursor material passes through the plasma block 620. The showerhead613 can then disperse the first precursor plasma into the etchingchamber 607, wherein the first precursor plasma can be adsorbed andreact on the exposed surfaces of the semiconductor device 100.

In an embodiment in which the first precursor material is NF₃, the firstprecursor material may be flowed into the plasma block 620 at a flowrate of between about 3 sccm and about 400 sccm, such as about 100 sccm.Additionally, once the first precursor material is turned into a plasma,the etching chamber 607 may be held at a pressure of between about 0.3torr and about 10 torr, such as about 2 torr, and a temperature ofbetween about 30° C. and about 150° C., such as about 100° C. However,as one of ordinary skill in the art will recognize, these processconditions are only intended to be illustrative, as any suitable processconditions may be utilized while remaining within the scope of theembodiments.

At the same time, the introduction of the second precursor material(e.g., NH₃) to the etching chamber 607 may be initiated by the controlunit 619 sending an instruction to the second precursor gas controller612 to connect the second precursor delivery system 606 (supplying thesecond precursor material) to the etching chamber 607 via the plasmablock 620 (or, if desired, a separate plasma block 620). Once connected,the second precursor delivery system 606 can deliver the secondprecursor material (e.g., NH₃) to the showerhead 613 through the plasmablock 620, with the plasma block 620 inducing the formation of thesecond precursor plasma as the second precursor material passes throughthe plasma block 620. The showerhead 613 can then disperse the secondprecursor plasma into the etching chamber 607, wherein the secondprecursor plasma can react with the first precursor plasma and the oxidematerial of the oxide layer 506 to remove the oxide layer 506.

In the embodiment in which the second precursor material is ammonia, thesecond precursor material may be flowed into the plasma block 620 at aflow rate of between about 20 sccm and about 400 sccm, such as about 100sccm. However, as one of ordinary skill in the art will recognize, theseprocess conditions are only intended to be illustrative, as any suitableprocess conditions may be utilized while remaining within the scope ofthe embodiments.

FIG. 7A illustrates that, once the oxide layer 506 portion of theprotection layer 406 is removed, the remaining portion of the protectionlayer 406 may be removed. In an embodiment, the removal of the remainingportion of the protection layer 406 may be achieved via a radical plasmaetch process. However, any suitable removal process may be used toremove the remaining portion of the protection layer 406.

During the radical plasma etch used to remove the remaining portion ofthe protection layer 406, a solid by-product material 701 may be formedon the surface of the semiconductor device 100, as shown in FIG. 7A. Thesolid by-product material 701 may prevent and/or repair damage to thefirst metal material layer 405 and/or may reinforce the integrity of thefirst metal material layer 405 in areas that become weakened duringetching of the remaining portions of the protection layer 406 and isdiscussed in greater detail later.

FIG. 7B illustrates the removal of the remaining portion of theprotection layer 406 via the radical plasma etch removal process in anetching chamber 607 using a remote plasma to remove the remainingportion of the protection layer 406 from the surface of thesemiconductor device 100. In an embodiment the radical plasma etchremoval process may be performed in situ within the etching system 600(described above with respect to FIG. 6B). In another embodiment theremaining portion of the protection layer 406 may be removed in aseparate etching chamber that comprises similar structures as describedfor the etching system 600.

In an embodiment the etching system 600 for the radical plasma etch mayutilize two or more precursor materials (e.g., the first precursormaterial and a third precursor material) to remove the remaining portionof the protection layer 406. For example, the etching system 600 mayutilize precursor materials from the first precursor delivery system 605and a third precursor delivery system 622 to generate an etchant used toremove the remaining portions of the protection layer 406 from thesemiconductor device 100. The removal of the remaining portions of theprotection layer 406 may be performed in the etching chamber 607 whichreceives radicals from the first precursor material and the thirdprecursor material.

The first precursor delivery system 605 and the third precursor deliverysystem 622 may work in conjunction with one another to supply thevarious different precursor materials to the etching chamber 607. Forexample, the third precursor delivery system 622 may comprise componentssimilar to the first precursor delivery system 605. For example, if thethird precursor material is in a gaseous state during preparation andstorage, the third precursor delivery system 622 may comprise a thirdprecursor material supplier, such as a gas storage tank or a machine togenerate the third precursor material on an as-needed basis. In anotherembodiment, if the third precursor material is in a liquid or solidstate during preparation and storage, the third precursor deliverysystem 622 may be implemented using a carrier gas and asublimation/vaporization process.

The third precursor delivery system 622 may supply a stream of the thirdprecursor material to, e.g., a third precursor gas controller 624, whichmay supply the third precursor material to the showerhead 613 withoutturning it into a plasma as the third precursor material (in anon-plasma phase) enters the etching chamber 607. In an embodiment thethird precursor gas controller 624 may be similar to the first precursorgas controller 611 (discussed above) and may include such devices asvalves, flow meters, sensors, and the like to control the connection anddelivery rate of the third precursor material to the showerhead 613. Thethird precursor gas controller 624 may also be controlled and receiveinstructions from the control unit 619.

The first precursor gas controller 611 and the third precursor gascontroller 624, upon receiving instructions from the control unit 619,may open and/or close valves so as to connect the first precursordelivery system 605 to the plasma block 620 and connect the thirdprecursor delivery system 622 to the etching chamber 607 and direct thedesired precursor materials to their respective destinations. Forexample, the first precursor gas controller 611 will direct the firstprecursor material to the plasma block 620 and the third precursor gascontroller 624 will direct the second precursor material to theshowerhead 613.

The showerhead 613 may be a multiple-zone showerhead utilized todisperse the chosen precursor materials into the etching chamber 607 andmay be designed to evenly disperse the precursor materials in order tominimize undesired process conditions that may arise from unevendispersal. In an embodiment in which two precursor materials areutilized the showerhead 613 may have a dual dispersion design thataccepts both the first precursor material (through, e.g., a first plasmainlet) and the third precursor material (through, e.g., a third inlet)at the same time and will disperse both the first precursor material andthe third precursor material in an even distribution around the etchingchamber 607. The showerhead 613 may have a circular design with openingsdispersed evenly around the showerhead 613 to allow for the dispersal ofthe first precursor material and the third precursor material into theetching chamber 607.

In an embodiment the control unit 619 also controls the activation of afilter 629 disposed, for example, within the plasma block 620. In anembodiment the filter 629 is utilized in order to separate elements ofthe plasma formed from the precursor materials provided to the plasmablock 620. In another embodiment, the filter 629 may be disposed withinthe etching chamber 607 between the inlet for the first precursor plasmaand the mounting platform 615. Any suitable placement may be utilized.

In an embodiment the filter 629 may be an electrically charged gratingthat acts as a barrier to the movement of charged ions from thegenerated plasma while allowing uncharged, neutral plasma components(e.g., neutral radicals) to pass through the filter 629. In anembodiment the filter 629 can prevent the charged plasma ions (e.g.,positively charged ions or negatively formed ions) from passing byeither repelling the charged plasma ions or else by attracting thecharged plasma ions. However, any suitable device that can separateradicals from a plasma may be utilized.

Once the first precursor plasma has been generated from the firstprecursor material, the first precursor plasma will comprise positiveions, negative ions, and neutral radical components disposed within thefirst precursor plasma. However, the filter 629 allows the neutralradical components to pass through the filter 629 and into the etchingchamber 607 where the semiconductor device 100 is located. Additionally,the filter 629 prevents the movement of the positive ions and also thenegative ions from entering the etching chamber 607. In effect, thefilter 629 is utilized to filter the positive ions and the negative ionsfrom the first precursor plasma, thereby allowing only or mainly theneutral radical components to be used.

To initiate the removal of the remainder of the protection layer 406,the control unit 619 sends a signal to the first precursor gascontroller 611 to start a flow of the first precursor material (e.g.,NF₃) to the plasma block 620 and also sends a signal to the thirdprecursor gas controller 624 to start a flow of the third precursormaterial (e.g., H₂) to the showerhead 613. In an embodiment to removethe protection layer 406, the first precursor material may be flowed ata flow rate of between about 10 sccm and about, such as about 200 sccm,while the third precursor material may be flowed at a flow rate ofbetween about 500 sccm and about 10000 sccm, such as about 5000 sccm. Assuch, the process may utilize a ratio of the first precursor material(e.g., NF₃) to the third precursor material (e.g., H₂) of between about0.2% and about 1.1%, such as about 0.56%. However, any suitable flowrates and ratios may be utilized.

By sending the first precursor material to the plasma block 620, thefirst precursor material will be turned into the first precursor plasmawhile the third precursor material remains in its original form (e.g.,not a plasma). Additionally, with the presence of the filter 629, thefirst precursor plasma will be separated into its individual components,and mainly or only the neutral radicals will enter the etching chamber607. As such, the precursors that enter the etching chamber include thethird precursor material and the neutral radicals from the plasma of thefirst precursor material.

Within the etching chamber, the third precursor material and the neutralradicals from the plasma of the first precursor material will react withthe exposed surfaces of the protection layer 406 (e.g., silicon). Thereaction can be performed at a pressure of less than about 5 Torr, suchas less than about 2 Torr and a temperature of between about 30° C. andabout 100° C., such as about 60° C. Additionally, the etching process toremove the remainder of the protection layer 406 may be performed for atime of between about 30 seconds and about 97 seconds, such as about 43seconds. However, any suitable process conditions may be utilized.

With the presence of the third precursor material and the neutralradicals from the plasma of the first precursor material, theseprecursors will react with the material of the protection layer 406(e.g., silicon) and will work to remove the remaining material of theprotection layer 406. As such, the protection layer 406 may be removedfrom covering the first metal material layer 405.

Additionally, in an embodiment, the reaction of the material of theprotection layer 406 with the precursors does not only remove thematerial of the protection layer 406. In addition, in an embodiment inwhich the protection layer 406 is silicon, the first precursor materialis NF₃ and the third precursor material is hydrogen, the reaction willalso form a solid by-product material 701 in a side reaction at the sametime that the reaction is removing the material of the protection layer406. In one such embodiment the solid by-product material 701 may be aby-product such as ammonium bifluoride (NH₄HF₂), and may be created(starting with an intermediate product) according to the reactionillustrated in Equation 1.

However, any suitable material that is a by-product and can be used toprotect the underlying layers may be utilized.

By depositing the solid by-product material 701, the solid by-productmaterial 701 can protect the underlying layers (e.g., the first metalmaterial layer 405) from undesired damage during the removal of theprotection layer 406. As such, process challenges such as metal gateextrusion and damage to the top of the fin, which may be susceptible tosuch damage, can be minimized or reduced during the removal of theremainder of the protection layer 406.

FIG. 7C illustrates another cross-sectional view of the semiconductordevice 100 after the removal of the protection layer 406. In this view,it can be seen that the first metal material layer 405 retains itsthickness over the top of the fin 107 instead of being reduced inthickness through the etching process. In particular, after the removalof the protection layer 406, the first metal material layer 405 over thetop of the fins 107 may have a first thickness T₁ of between about 5 Aand about 60 A, such as about 15 A, while the first metal material layer405 along the sidewalls of the fins 107 may have a second thickness T₂that is less than the first thickness T₁, such as being between about 5A and about 60 A, such as about 15 A.

As such, the first metal material layer 405 remains continuous after theremoval of the protection layer 406. In particular, the process mayincrease the thickness that remains after the etching process (ascompared to previous processes) of about 1.5 nm. Similarly, the removalof material of the first metal material layer 405 is improved by about30% when compared to previous removal processes.

FIG. 8 illustrates that, once the protection layer 406 has been removedand the etching process has been finished, the solid by-product material701 may be removed. In an embodiment the solid by-product material 701may be removed by simply raising the temperature of the solid by-productmaterial 701 above the triple point of the material of the solidby-product material 701. As such, in an embodiment in which the solidby-product material 701 is ammonium bifluoride, the solid by-productmaterial 701 may be removed by raising the temperature of the ammoniumbifluoride above 125° C. while at a pressure of about 40 Torr. However,any suitable temperature and pressure may be utilized.

In another embodiment, instead of utilizing the triple point of thematerial of the solid by-product material 701 to cause the solidby-product material 701 to sublimate, a chemical removal process may beutilized. In such an embodiment a wet etch or a dry etch process whichutilizes etchants that are selective to the material of the solidby-product material 701 may be utilized to remove the solid by-productmaterial 701. However, any suitable removal process may be utilized.

By utilizing the neutral radical etch along with the solid by-productmaterial 701 as protection, damage and defects can be avoided. In someembodiments, the device formed can see an IO Vdb improvement of about2V, while an time-dependent gate oxide breakdown (nTDDB) can have anenhancement of +17 mV with no appreciable degradation in time tobreakdown. Similarly, the number of defects on a wafer can be reducedfrom about 1343 (as a baseline number) to 1110 (using a NF₃:H₂ ratio of0.5% for 43 seconds at a pressure of 2 Torr and a temperature of 40° C.)or even 530 (using a NF₃:H₂ ratio of 1.1% for 30 seconds at a pressureof 1 Torr and a temperature of 40° C.). Additionally, n-type devices cansee a 0.56% improvement in the threshold voltage (NSVT) utilizing theembodiments described herein.

FIG. 9 illustrates a formation of a work function layer 901 over thefirst metal material layer 405. The work function layer 901 may bechosen based upon the type of device desired. Exemplary p-type workfunction metals that may be included include Al, TiAlC, TiN, TaN, Ru,Mo, WN, ZrSi₂, MoSi₂, TaSi₂, NiSi₂, WN, other suitable p-type workfunction materials, or combinations thereof. Exemplary n-type workfunction metals that may be included include Ti, Ag, TaAl, TaAlC, TiAlN,TaC, TaCN, TaSiN, Mn, Zr, other suitable n-type work function materials,or combinations thereof. A work function value is associated with thematerial composition of the work function layer 901, and thus, thematerial of the work function layer 901 is chosen to tune its workfunction value so that a desired threshold voltage Vt is achieved in thedevice that is to be formed in the respective region. The work functionlayer(s) may be deposited by CVD, PVD, and/or other suitable process toa thickness of between about 5 Å and about 50 Å.

A metal layer 903 may be formed over the work function layer 901. In anembodiment the metal layer 903 may be a material that is both suitablefor use as a seed layer to help a subsequent filling process as well asa material that can be used to help block or reduce the transport offluorine atoms into the work function layer 901. In a particularembodiment, the metal layer 903 may be crystalline tungsten (W) that isformed free from the presence of fluorine atoms and formed using aprocess such as atomic layer deposition or chemical vapor depositionwhich utilizes precursor free from fluorine. However, any suitablematerial and method of formation may be utilized.

A nucleation layer 905 may be formed over the metal layer 903 in orderto provide a nucleation point for a subsequent fill material 907. In anembodiment the nucleation layer 905 may be the same material as themetal layer 903 (e.g., tungsten), may be formed using a similar process(e.g., ALD), but may be deposited without fluorine free precursors.Additionally, while the metal layer 903 may be a crystalline (e.g.,crystalline tungsten), the nucleation layer 905 may be formed to be anamorphous material, such as amorphous tungsten.

Once the nucleation layer 905 has been formed, a fill material 907 isdeposited to fill a remainder of the opening using the nucleation layer905 to help nucleate the fill material 907. In an embodiment the fillmaterial 907 may be the same material as the nucleation layer 905 (e.g.,tungsten) or may be a different material, such as Al, Cu, AlCu, W, Ti,TiAlN, TaC, TaCN, TaSiN, Mn, Zr, TiN, Ta, TaN, Co, Ni, combinations ofthese, or the like, to a thickness of between about 1000 Å and about2000 Å, such as about 1500 Å. However, any suitable material may beutilized.

Additionally, the fill material 907 may be deposited using a depositionprocess such as a non-conformal deposition process such as chemicalvapor deposition. In an embodiment the deposition process may utilizeprecursors such as tungsten fluoride (WF₆) and hydrogen (H₂), althoughany suitable precursors may be utilized. In a particular embodimentusing tungsten fluoride and hydrogen as the precursors, the tungstenfluoride may be flowed into a reaction chamber at a flow rate of betweenabout 0.1 slm and about 0.5 slm, such as about 0.3 slm, while thehydrogen may be flowed in at the same time at a flow rate of betweenabout 1 slm and about 10 slm, such as about 6 slm. Additionally, thechemical vapor deposition process may be performed at a temperature ofbetween about 200° C. and about 400° C., such as about 300° C., and at apressure of between about 100 torr and about 400 torr, such as about 250torr. However, any suitable process conditions may be utilized.

FIG. 10 illustrates that, after the fill material 907 has been depositedto fill and overfill the opening, any excess material outside of theopening may be planarized to form the gate stack 1001. In an embodimentthe materials may be planarized with the first spacers 113 using, e.g.,a chemical mechanical polishing process, although any suitable process,such as grinding or etching, may be utilized.

After the materials of the gate stack 1001 have been formed andplanarized, the materials of the gate stack 1001 may be recessed andcapped with a capping layer 1003. In an embodiment the materials of thegate stack 1001 may be recessed using, e.g., a wet or dry etchingprocess that utilizes etchants selective to the materials of the gatestack 1001. In an embodiment the materials of the gate stack 1001 may berecessed a distance of between about 5 nm and about 150 nm, such asabout 120 nm. However, any suitable process and distance may beutilized.

Once the materials of the gate stack 1001 have been recessed, thecapping layer 1003 may be deposited and planarized with the firstspacers 113. In an embodiment the capping layer 1003 is a material suchas SiN, SiON, SiCON, SiC, SiOC, combinations of these, or the like,deposited using a deposition process such as atomic layer deposition,chemical vapor deposition, sputtering, or the like. The capping layer1003 may be deposited to a thickness of between about 5 Å and about 200Å, and then planarized using a planarization process such as chemicalmechanical polishing such that the capping layer 1003 is planar with thefirst spacers 113.

After the capping layer 1003 has been formed, additional processing maybe performed. For example, a source/drain contact (not separatelyillustrated in FIG. 10) may be formed to make electrical connection tothe source/drain region, and a gate contact (also not separatelyillustrated in FIG. 10) may also be formed through the capping layer1003 in order to make electrical connection to the gate stack 1001.Further, metallization layers may be formed in contact with thesource/drain contact and the gate contact in order to provide routingand functionality to the device. Any suitable further processing may beutilized.

By utilizing the embodiments described herein, surface damage to thedevices formed which can cause the voltage breakdown to grow worse byabout 2.0 V can be mitigated or eliminated, allowing for a betteroverall process window (e.g., a reduction of the limit of line-end byabout 2 nm). This is especially true with high aspect ratios and roughsurfaces.

In accordance with an embodiment, a method of manufacturing asemiconductor device includes forming an etching plasma from a firstprecursor material; separating neutral radicals of the etching plasma;and exposing surfaces of a protective layer over a gate dielectric tothe neutral radicals of the etching plasma and a second precursormaterial to etch portions of the surfaces of the protective layer, thesecond precursor material not being a plasma. In an embodiment themethod further includes performing an annealing process on the gatedielectric, wherein the annealing process oxidizes a portion of theprotection layer to form an oxidized portion, the annealing processbeing performed before the forming the etching plasma; forming an oxideetching plasma from the first precursor material and a third precursormaterial, the third precursor material being different from the firstprecursor material and the second precursor material; and using theoxide etching plasma to remove the oxidized portion. In an embodimentthe first precursor material is nitrogen trifluoride, the secondprecursor material is hydrogen, and the third precursor material isammonia. In an embodiment the separating the neutral radicals of theetching plasma comprises activating a filter that prevents positive ionsand negative ions of the etching plasma from passing through the filter.In an embodiment the exposing the surfaces of the protective layer isperformed at a temperature at or below 100° C. while at a pressure ofless than or equal to 5 Torr. In an embodiment the protective layer issilicon. In an embodiment the exposing the surfaces of the protectivelayer further deposits a solid by-product material.

In accordance with another embodiment, a method of manufacturing asemiconductor device includes depositing a first dielectric layer over achannel region of a semiconductor fin; forming a first metal barrierlayer over the first dielectric layer; forming a protective layer overthe first metal barrier layer; performing an annealing process, whereinthe annealing process oxidizes a portion of the protection layer to forman oxidized portion; using a plasma etching process to remove theoxidized portion; and after the using the plasma etching process, usinga radical plasma etching process to remove the protection layer, whereinthe radical plasma etching process includes forming a first plasma froma first precursor; activating a filter to separate neutral radicals frompositive radicals and negative radicals; sending the neutral radicals toan etching chamber; and introducing a non-plasma precursor into theetching chamber with the neutral radicals. In an embodiment the radicalplasma etching process produces a solid by-product layer. In anembodiment the method further includes removing the solid by-productlayer after the radical plasma etching process. In an embodiment theremoving the solid by-product layer is performed at least in partthrough a sublimation process. In an embodiment the solid by-productlayer comprises ammonium bifluoride. In an embodiment the firstprecursor is nitrogen trifluoride and the non-plasma precursor ishydrogen. In an embodiment the plasma etching process includes formingthe first plasma from the first precursor; forming a second plasma froma second precursor; and introducing the first plasma and the secondplasma to the oxidized portion.

In accordance with yet another embodiment, a method of manufacturing asemiconductor device includes removing a dummy gate from over asemiconductor fin; depositing a barrier layer over the semiconductorfin; depositing silicon over the barrier layer; oxidizing a portion ofthe silicon to form a layer of silicon oxide and a remaining portion ofthe silicon; removing the layer of silicon oxide; reacting the remainingportion of the silicon, wherein the reacting the remaining portion ofthe silicon both removes the silicon as well as deposits a solidprotective material; and removing the solid protective material. In anembodiment the solid protective material comprises ammonium bifluoride.In an embodiment the removing the solid protective material comprisessublimating the solid protective material. In an embodiment the reactingthe remaining portion of the silicon comprises introducing neutralradicals from a first precursor material. In an embodiment the neutralradicals pass through an activated filter prior to reacting with theremaining portion of the silicon. In an embodiment the removing thelayer of silicon oxide comprises introducing neutral radicals, positiveradicals, and negative radicals from the first precursor material.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of manufacturing a semiconductor device,the method comprising: forming an etching plasma from a first precursormaterial; separating neutral radicals of the etching plasma, wherein theseparating the neutral radicals of the etching plasma comprisesactivating a filter that prevents positive ions and negative ions of theetching plasma from passing through the filter; and exposing surfaces ofa protective layer over a gate dielectric to the neutral radicals of theetching plasma and a second precursor material to etch portions of thesurfaces of the protective layer, the second precursor material notbeing a plasma.
 2. The method of claim 1, further comprising: performingan annealing process on the gate dielectric, wherein the annealingprocess oxidizes a portion of the protection layer to form an oxidizedportion, the annealing process being performed before the forming theetching plasma; forming an oxide etching plasma from the first precursormaterial and a third precursor material, the third precursor materialbeing different from the first precursor material and the secondprecursor material; and using the oxide etching plasma to remove theoxidized portion.
 3. The method of claim 2, wherein the first precursormaterial is nitrogen trifluoride, the second precursor material ishydrogen, and the third precursor material is ammonia.
 4. The method ofclaim 1, wherein the exposing the surfaces of the protective layer isperformed at a temperature at or below 100° C. while at a pressure ofless than or equal to 5 Torr.
 5. The method of claim 1, wherein theprotective layer is silicon.
 6. The method of claim 1, wherein theexposing the surfaces of the protective layer further deposits a solidby-product material.
 7. The method of claim 1, wherein activating thefilter comprises electrically charging a grating.
 8. A method ofmanufacturing a semiconductor device, the method comprising: depositinga first dielectric layer over a channel region of a semiconductor fin;forming a first metal barrier layer over the first dielectric layer;forming a protective layer over the first metal barrier layer;performing an annealing process, wherein the annealing process oxidizesa portion of the protection layer to form an oxidized portion; using aplasma etching process to remove the oxidized portion; and after theusing the plasma etching process, using a radical plasma etching processto remove the protection layer, wherein the radical plasma etchingprocess comprises: forming a first plasma from a first precursor;activating a filter to separate neutral radicals from positive radicalsand negative radicals; sending the neutral radicals to an etchingchamber; and introducing a non-plasma precursor into the etching chamberwith the neutral radicals.
 9. The method of claim 8, wherein the radicalplasma etching process produces a solid by-product layer.
 10. The methodof claim 9, further comprising removing the solid by- product layerafter the radical plasma etching process.
 11. The method of claim 10,wherein the removing the solid by-product layer is performed at least inpart through a sublimation process.
 12. The method of claim 9, whereinthe solid by-product layer comprises ammonium bifluoride.
 13. The methodof claim 8, wherein the first precursor is nitrogen trifluoride and thenon-plasma precursor is hydrogen.
 14. The method of claim 13, whereinthe plasma etching process comprises: forming the first plasma from thefirst precursor; forming a second plasma from a second precursor; andintroducing the first plasma and the second plasma to the oxidizedportion.
 15. A method of manufacturing a semiconductor device, themethod comprising: removing a dummy gate from over a semiconductor fin;depositing a barrier layer over the semiconductor fin; depositingsilicon over the barrier layer; oxidizing a portion of the silicon toform a layer of silicon oxide and a remaining portion of the silicon;removing the layer of silicon oxide; reacting the remaining portion ofthe silicon, wherein the reacting the remaining portion of the siliconboth removes the silicon as well as deposits a solid protectivematerial; and removing the solid protective material.
 16. The method ofclaim 15, wherein the solid protective material comprises ammoniumbifluoride.
 17. The method of claim 15, wherein the removing the solidprotective material comprises sublimating the solid protective material.18. The method of claim 15, wherein the reacting the remaining portionof the silicon comprises introducing neutral radicals from a firstprecursor material.
 19. The method of claim 18, wherein the neutralradicals pass through an activated filter prior to reacting with theremaining portion of the silicon.
 20. The method of claim 18, whereinthe removing the layer of silicon oxide comprises introducing neutralradicals, positive radicals, and negative radicals from the firstprecursor material.